As one of the processes of manufacturing a semiconductor device, a substrate processing process including a step of cleaning the surface of a substrate by using a hydrogen chloride gas and a step of cleaning the surface of the substrate by using a gas containing silicon halide and a chlorine gas is often carried out. A substrate processing process in which a step of epitaxially growing a silicon film on a substrate and a step of partially etching the silicon film by using a hydrogen chloride gas are alternately performed is also often carried out.